1.1. Field
The present disclosure relates generally to communication, and more specifically to techniques for supporting emergency calls.
1.2. Background
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and so on. These wireless networks may be multiple-access networks capable of supporting communication for multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, and Orthogonal FDMA (OFDMA) networks.
Wireless networks typically support communication for wireless users that have service subscriptions with these networks. A service subscription may be associated with information for security, routing, quality of service (QoS), billing, and so on. The subscription-related information may be used to establish calls with a wireless network.
One of the most basic services provided by wireless networks for its users is the ability to send and receive voice calls. One recent enhancement of this service is the ability to send and receive Voice over Internet Protocol (VoIP) calls. A VoIP call is a voice call in which voice data is sent in packets that are routed like other packet data instead of on dedicated traffic channel.
A wireless user may place an emergency voice or other media call with a wireless network that may or may not be a home network with which the user has service subscription. Such a call may use VoIP. A major challenge is to route the emergency call to an appropriate Public Safety Answering Point (PSAP) that can service the call. This may entail obtaining an interim position estimate for the user and determining the proper PSAP based on the interim position estimate. The problem is compounded if the user is roaming and/or has no service subscription with any network.
There is therefore a need in the art for techniques to support emergency calls and emergency VoIP calls.